A highly diastereoselective one-pot Ugi/radical spirocyclization/aza-Michael addition sequence

Area of Science:

• Organic synthesis
• Medicinal chemistry
• Photochemistry

Background:

• Azaspirotricycles are important heterocyclic scaffolds with diverse biological activities.
• Efficient and stereoselective synthetic routes to complex azaspirotricycles remain challenging.
• Chalcogenation introduces unique properties relevant to drug discovery and materials science.

Purpose of the Study:

• To develop a novel, highly diastereoselective synthesis of chalcogenated azaspirotricycles.
• To explore a one-pot Ugi/spirocyclization/aza-Michael addition sequence.
• To utilize visible light mediation for an energy-efficient and metal-free process.

Main Methods:

• A one-pot multi-component reaction involving Ugi, spirocyclization, and aza-Michael addition.
• Visible light photoredox catalysis to mediate the key spirocyclization step.
• Characterization of synthesized sulfenylated and selenylated azaspirotricycles using standard spectroscopic techniques.

Main Results:

• Achieved highly diastereoselective synthesis of complex sulfenylated and selenylated azaspirotricycles.
• The reaction proceeds under mild, metal-free, and energy-efficient conditions.
• Demonstrated scalability of the synthetic methodology with good yields.
• Preliminary mechanistic studies suggest a radical intermediate pathway for spirocyclization.

Conclusions:

• A novel and efficient one-pot strategy for synthesizing chalcogenated azaspirotricycles has been established.
• The developed method offers a sustainable and scalable approach using visible light.
• The findings provide a valuable platform for accessing novel heterocyclic compounds with potential applications.